Analysis of wear characteristics of natural rubber nanocomposites

Tribological characteristics of natural rubber nanocomposites for wear resistant applications have been studied by sliding against a steel blade, in a specially designed abrader. Testing parameters have been optimized for minimum wear based on Taguchi orthogonal design with four important parameters, viz., nanofiller loading, applied normal load, speed and time of run. Amongst these, nanofiller loading has the most significant influence on wear characteristics. In spite of the high normal pressure acting at the line of contact, certain well established power law relations are found to obey in principle, as wear increases with normal load and frictional work, Fw. Analysis of the micrographs of the abraded surface and the corresponding debris reveals that the specific wear rate of both the nanocomposites (sepiolite and carbon nanofiber filled) is found to increase beyond a critical fractal dimension, i.e., with increasing structural complexity of the debris formed. The rate of wear decreases steeply with nanofiber loading as compared to sepiolite. The changes in temperature build up and dynamic coefficients of friction are found to be concomitant. The wear mechanism is found to be fatigue at low frictional work, followed by frictional wear at high Fw.